Electric contact means



I United States Patent 11 13,551,629

[72] Inventor Samuel Berg [56] References Cited Ludvika, Sweden UNITEDSTATES PATENTS I 1 PP No. 823,771 2,300,893 11 1942 Hayford ZOO/166(E)[22] F l d May 12,1969 2.324,89l 7/1943 Thumim 200/166(l-l)(X) I 1 Famed2,891,134 6/1959 Ramrath 200/170 [73] Assignee Allmanna SvenskaElektriska Aktiebolaget 3,009,043 1 H1961 Goodwin JR et ZOO/166(5)vasterisr swede" 3,127,492 3/1964 Date ZOO/166(Bl) a SwedishCorporation. [32] Priority May 15, 1968 Primary Examiner-H. 0. Jones 33]Sweden Attorney-Jennings Bailey, Jr. [3 l No. 6524/68 [54] gg ig lz gABSTRACT: In a contact arrangement for circuit breakers an g lgelongated contact element is arranged resiliently in a contact [52] US.Cl 200/166 element holder and provided at one end with a contact tip of[SI] Int. Cl H0lh 1/48 arc-resistant contact metal. To attach thecontact tip to the [50] Field of Search 200/ 1668], contact element. thecontact tip is provided with an anchoring 16683, 16635. 166B6, 16688,166C, 166D, 166E, l66l-l, 146, 150.5, l70all fin engaging in a groove inthe contact element and projecting behind a supporting edge on thecontact element holder.

ELECTRIC CONTACT MEANS BACKGROUND OF THE INVENTION scorch marks fromappearing on the main contact surface of lo the contact element whichnormally consists of silver-plated or otherwise surface-treated copper,Le. a material having good electrical conductivity but relatively littleresistance to arcing. In order to fulfill this purpose the contact tipis placed so that the base points of an are formed duringshort-circuiting or breaking arise on the tip and remain there.

2. The Prior Art The most usual method of attaching the contact tip tothe contact element is soldering, an attachment method requiringconsiderable time and thus making the contact means more expensive. Theheating of the contact element required for the soldering also has thedisadvantage that the copper becomes softer. This entails a greater riskthat the contact element will bend, which may, cause the silver layer tofiakeoff. Even from the point of view of mechanical wear a soft materialis unsuitable for the contact element. Furthermore, if the soldering isnot carried out carefully, there is a risk that the contact tip mayloosen and cause considerable damage.

SUMMARY OF THE INVENTION The object of the present invention if toprovide a contact means in which the contact tip is fixed to the contactelement A in such a way that the above mentioned disadvantages withpreviously known contact means are avoided as far as possi' ble. This isachieved according to the invention by providing the contact tip on theside of the tip facing away from the contact surface with a projectinganchoring fin which is arranged to engage like a hook in a groove in thecontact element and to project behind a supporting edge of the contactelement. said supporting edge being arranged at that end of the contactele ment which is situated nearest the contact tip. By attaching thecontact tip in this way its manufacture is considerably simplified andan improvement in quality is obtained over the conventional solderingmethod since'no'damaging heating of the contact element is required.

The supporting edge arranged on the contact element holder is suitablydesigned to form a stop for the tip as well as for the movement of thecontact element. Since the movement of the contact element is limited bythe tip meeting the supporting edge, the contact force between the tipand the contact element is maintained even when one contact member ofthe contact means during a breaking process is at some distance from theother contact member and an arc exists so that the current flows throughthe tip to the contact element.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be furtherdescribed with reference to the accompanying drawings which show variousembodiments of the invention. FIG. I shows in axial section a sheathcontact means. FIGS. 2. 3 and 4 show three projections at right anglesto each other of a contact tip in the contact means shown in FIG. 1.FIG. 5 shows a knife contact means and FIG. 6 a pressure contact means.Contact tips of the type shown in FIGS. 2- -4 are also included in thecontact means according to FIGS. 5 and 6.

DESCRIPTION OF THE PREFERRED EMBODIMENTS ring 5 of copper-tungsten. Thecontact element 3 is pressed radially inward with the help of helicalsprings 6 which. in the closed position of the contact means effect thenecessary pressure between the contact element 3 and the movable contactplug 2 and between the contact element 3 and a pegshaped contact part 7arranged at the bottom of the sheath contact. At its front end eachcontact element 3 is provided with a contact tip 8, shown in detail inFIGS. 2-4. The contact tip 8 is made of copper-tungsten and is sinteredto its final shape. On the side of the tip 8 facing away from itscontact surface 9 the tip is provided with a projecting anchoring fin10. The fin 10 extends in the longitudinal direction of the contactelement 3 beyond both ends of the tip so that two projections 11 and 12are formed. In the contact element 3 is a recess 13 in the form of atransverse groove. open at the front. in which the tip 8 is inserted.The contact element 3 is also provided with a longitudinal groove 14 onits opposite side in which the fin 10 of the tip is guided. Thebackwardly directed projection 11 of the fin effects a grip which locksthe rear end of the tip. The frontwardly directed projection 12 of thepin abuts a supporting edge 15 on the arcing ring 5, which is designedso that the ring 5 prevents the tip 8 from tilting or gliding forwards.

When the movable contact plug 2 is in position to make contact and thetip 8 is to carry current, the contact surface between the tip 8 and thecontact element 3 has the same contact force as the contact surfacebetween the tip 8 and the movable contact plug 2, In completely closedposition the current transmission takes place directly between themovable contact plug 2 and the copper contact element 3.

When the movable contact 2 during a breaking process is at some distancefrom the contact element an arc exists which carries current through thetip 8 to the contact element 3. Also in this case, therefore. sufficientcontact force is required between the tip 8 and the contact element 3.This contact force is obtained since the stop between the tip 8 and thesupporting edge 15 also provides a stop for the movement of the contactelement 3. Hence, the spring force acting on the contact element 3 istransmitted to the tip 8.

FIG. 5 shows a knife contact means with a stationary cliptype contact 16and a movable contact knife 17. The clip-type contact 16 has two or morecontact elements 3 with contact tips 8, which are attached in the sameway as in the arrangement according to FIG. 1. The contact elements 3are arranged in a contact element holder 18 which is provided at thefront with a supporting edge 19.

FIG. 6 shows a section through a pressure contact means which isrotationally symmetrical about the axis shown in dotted lines. Thecontact means comprises a number of contact elements 3 which arearranged in a stationary contact element holder 20. The movable contactmember of the contact means consists of a contact sheath 21. The contactelements 3 are provided with contact tips 8 shaped and attached in thesame way as described in connection with FIG. I. The supporting edge ofthe contact element holder is in this case designated 22. At the rearside of the contact elements 3 a It is obvious from the embodimentsshown that the inven- 7 tion can be used in several different contactmeans. However, the invention is not limited to the embodiments shown,but many modifications are feasible within the scope of the followingclaims. For example with a sheath contact according to FIG. 1, insteadof the helical springs 6 leaf springs may be used which are designed sothat they yield edgewise, in which case one and the same groove in thecontact element 3 can be used both to retain the springs and to guidethe contact tip 8.

I claim: v

1. An electric contact means having two cooperating contact members, acontact element holder having an inwardly directed supporting edge, oneof said contact members comprising at least one elongated contactelement, said contact element movably mounted in said contact elementholder and provided at one end with a contact tip of arc-resistantcontact metal, said contact tip having a contact surface, meansresiliently urging said contact element in the direction of said contactsurface,'said contact element having a groove therein, said contact tipprovided with an anchoring fin projecting from that side of the contacttip facing away from its contact surface, said anchoring fin includinghook means engaging in said groove in said contact element and aprojection protecting behind said supporting edge on said contactelement holder, said supporting edge arranged at that end of saidcontact holder which is situated nearest said contact tip.

2. Electric contact means according to claim 1, in which said anchoringfin extends beyond both ends of said contact ,tip in the longitudinaldirection of said contact element.

stop for the tip as well as for the movement of the contact element.

